What Is a Subarachnoid Hemorrhage?

Subarachnoid hemorrhage (SAH) refers to bleeding within the subarachnoid space, which is the area between the brain and the tissues that cover the brain.

The subarachnoid space is the space through which the cerebrospinal fluid circulates and it is responsible for protecting the brain from serious injuries by serving a sort of cushion. When a hemorrhage occurs in this space, a person may experience coma, paralysis, and even death.

This condition can occur rapidly, and the key to survival is immediate medical intervention. If you or someone you know are experiencing the symptoms of SAH, call a doctor or emergency health professional as soon as possible.

Luckily, this life-threatening condition is rare. According to the Brain Aneurysm Foundation, SAH accounts for a tiny sliver of emergency room visits: between 0.02 and 0.08 percent (BAF).

Symptoms of SAH

When SAH develops, it creates some marked symptoms. The main symptom is a severe headache, which is more intense at the base of the skull. Some patients may even feel a popping sensation in the head before the hemorrhage begins.

You may also experience:

neck pain

numbness throughout your body

shoulder pain

seizures

confusion

irritability

sensitivity to light

decreased vision

nausea

vomiting

rapid loss of alertness

Symptoms of SAH come on suddenly and you may lose consciousness quickly. If you experience any of these symptoms combined with a severe headache, it is important to seek emergency medical attention right away.

Causes of SAH

SAH is related to brain aneurysms, which are abnormalities within the brain’s arteries. The most common cause of primary SAH is a congenital “berry” aneurysm. It is called a berry aneurysm because it forms a cluster of sac-like pouches in a cerebral vessel—looking like a cluster of berries. These aneurysms swell up and weaken the walls of arteries over time. When an aneurysm erupts, it quickly bleeds and forms a clot. This condition is responsible for about 85 percent of SAH cases. Aneurysmal hemorrhage may occur at any age but is most common from age 40 to 65. In some cases, trauma to the brain during an injury can cause aneurysms and result in a subarachnoid hemorrhage.

Other causes of SAH include:

bleeding from an arteriovenous malformation (AVM)

bleeding disorders

use of blood thinners

A serious head injury—such as occurs in a car crash or when an older person falls and hits their head—can also lead to an SAH.

Risk Factors for SAH

SAH can occur at any age, and some people are even born with cerebral aneurysms that can lead to this condition. According to the National Institute of Neurological Disorders and Stroke, women are more likely to develop SAH than men.

If you have aneurysms, it is important to see your doctor regularly to help detect the potential for hemorrhaging before SAH develops.

Diagnosing SAH

This condition is often detected during a physical exam. A doctor may notice a stiff neck and vision problems—a combination that oftentimes leads to a diagnosis of SAD. Further testing is required to determine the severity of the hemorrhage so that proper treatment can be administered.

First, your doctor may conduct a computed tomography (CT) scan of the head to detect bleeding in the skull. If the results are inconclusive, the doctor may use a contrast dye during the procedure. According to the National Institutes of Health, up to 10 percent of SAH patients have normal CT results, which is why this isn’t the only test used to diagnose the condition (NIH).

Other tests include:

magnetic resonance imaging (MRI) scan, using radiowaves to get clear detailed images of the brain

cerebral angiography—an exam that uses a X-ray and injected dye to detect blood flow in the brain

transcranial ultrasound to detect blood flow in the arteries within the brain

Treating SAH

Rapid treatment is important to save your life and reduce the possibility of brain damage. Surgery is performed to first close the aneurysm (clip the aneurysm) and stop future bleeding, and then to provide a more permanent repair to the aneurysm.

In order clip the aneurysm, a craniotomy (opening the skull to expose the area of involvement) is performed and the aneurysm is closed. A technique called endovascular coiling may also be used to reduce the risk of further bleeding.

If SAH causes a coma, treatment will include appropriate life support with artificial ventilation, protection of the airways, and placement of a draining tube in the brain to relieve pressure.

If you don’t lose consciousness as part of SAH, you will still be given strict instructions to prevent post-treatment coma. Bed rest is standard for patients recovering from this condition. You will also be instructed to refrain from straining your body or bending over because these actions can increase pressure on the brain.

Complications of SAH

Even after SAH treatment, you may be at risk for related complications. According to the National Institutes of Health, repeated hemorrhages are the most common complications of SAH (NIH). Repeated bleeding can increase your risk of death. Comas due to SAH can also eventually lead to death.

In some cases, patients may experience seizures or strokes following treatment.

Preventing SAH

The only way to prevent this condition is to identify potential problems within the brain. Early detection and, in some cases, treatment of a brain aneurysm can prevent a subsequent hemorrhage in the subarachnoid space.

Long-Term Outlook

SAH is a serious condition that can be fatal. The recovery period is long, and you may be at a higher risk of complications if you are older or have poor overall health.

Treatment is not a guarantee; some patients die even after the most aggressive medical interventions. The earlier you seek emergency medical care, the better your chances of survival.